636
FXUS65 KGGW 061107
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
507 AM MDT Mon May 6 2024

.DISCUSSION...
KEY MESSAGES:

- There is a High Wind Warning for much of the area for very
  strong winds today through Tuesday night, leading to crosswind
  concerns on area roadways and dangerous chop on Fort Peck Lake.

- Widespread rain today through Wednesday night. Weather
  Prediction Center has issued a Slight Risk for Excessive
  Rainfall for the 24 hr period ending on 6am Tuesday.

- Flood concerns increasing for small streams Tuesday and
  Wednesday, leading to rises along the Milk River late in the
  week.

WEATHER PATTERN OVERVIEW:

A stacked low pressure system will lift from the central Rockies
into the northern Plains today, then linger over the region
through Tuesday night. The low will then begin to drift southeast
as a latitudinal ridge folds south toward the Canadian border
through the end of the week. By the weekend a flat ridge will push
from the Pacific Northwest across the northern Rockies.

CONFIDENCE AND POTENTIAL DEVIATIONS FROM BASE FORECAST:

Probabilities for high wind have decreased slightly with both
speed and area. Still looking at high probability (70-90%) for
wind gusts over 55 mph for Phillips county (excluding the north),
Petroleum and Garfield counties. For Prairie county the high
winds will be mostly in the west over the Big Sheeps, and Valley
county will see the strongest winds across the ridge tops near
Fort Peck Lake. So have upgraded these zones to a High Wind
Warning. Other zones in the watch will have much lower probability
for reaching high wind criteria, so cancelled that portion of the
watch.

Rainfall amounts for the region from today through Wednesday night
remain very high. Probability for at least 1 inch is over 70% for
the entire region. Confidence for 2 inches or more drops off to
30-50% east of Opheim, Poplar and Glendive while staying at 60-90%
for most of the area to the west. Probability for more then 3
inches is not insignificant, setting at 30-40% for Malta, Glasgow
and Jordan, and peaking at 60% around the Little Rockies.

With the widespread high precipitation amounts, flooding will
become a concern from midweek into the weekend. RFC forecasts are
putting the Milk River at Tampico and Glasgow above flood stage by
the end of the week. Small stream flooding and impassable gravel
roads are also expected mainly for Phillips, Valley and Garfield
counties.

&&

.AVIATION...
VFR, dropping to IFR as showers move north through the day.
Low clouds and occasional reduced visibility will linger through
Tuesday as a low pressure system keeps rain over the region. With
the low pressure, winds will be turning from east to northwest
throughout the day, and increasing to 20-30kts with gusts to
40kts after 0z Tuesday.

&&

.GGW WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 9 AM this morning to midnight MDT Tuesday
night for Central and Southeast Phillips-Central and Southern
Valley-Garfield-Petroleum-Prairie-Southwest Phillips.

&&

$$

weather.gov/glasgow